In a short glittery dress, Rebel Wilson pops like a sparkler against the blankness of a Hollywood photo studio. Her hair is piled high on her head, and her lashes arc like black fans, framing a faraway look. There's something about the scene that's reminiscent of Botticelli's The Birth of Venus—her hair guy, like a winged genius, propels a breeze in her direction, while her stylist, like an attending Grace, adjusts the folds of her dress. Photos of '60s sex symbols (Bardot, etc.) are taped to the wall for inspiration, and Wilson channels them like it's nothing—just another day in her life as an international sex symbol. Watching her vamp for the camera is a revelation. This isn't camp. She's not playing at being beautiful. And it kind of knocks you out.

ABC is banking on her to confer some of that magic on its new lineup. Headlined by Wilson, Super Fun Night is a sitcom about a trio of social misfits who decide the time has come to stop hiding from the world and start having a good time. The show has been bestowed the privileged slot following Modern Family, and Wilson is being heavily promoted as network TV's biggest new star. But more than just a vehicle for her impeccable comic timing, the show, which she created, writes, and stars in, is also bound up in her unique brand of It Girl. Her comedic persona—she's a hilarious, sexy, bawdy, brave, and totally shameless XXL girl in a fat-shaming culture that reserves its most vicious opprobrium for women—seems engineered to explode every stereotype it comes across.

Since her lunatic turn two years ago as Kristen Wiig's worst-nightmare roommate in Bridesmaids, Wilson has generated an inordinate amount of buzz for someone whose roles have mostly been supporting—or at least intended to be. In movies like Pitch Perfect and Bachelorette, she combines unapologetic sexiness, exuberant crudeness, and a sweet vulnerability. It's not only that her characters are either oblivious to how they're perceived or that they just don't care; their clueless innocence saves them from their total absence of a filter. She makes boorishness look adorable.

And herein lies her genius, as well as her power: Wilson avoids being put into boxes by pretending to be unaware of the presence of boxes. And in doing so, she changes the rules of the game. She understands that if she wants to get where she's going, she has to be the captain of her own ship. She may identify with the underdog, but she thinks and operates like an alpha.

"I don't know where it comes from," says her friend, roommate, and Bridesmaids costar Matt Lucas of her enormous chutzpah, though he posits that it could have been forged during her days at an elite all-girls boarding school in suburban Sydney, Australia, where Wilson says she was terribly unpopular.

"I remember just sitting down one day and going, 'I should have friends,' " Wilson tells me. "And then I developed a sense of humor. By the end of high school, I would say I was the most popular girl." Wilson became well-known throughout the school for pranks like stealing alarm codes to facilitate escapes, masterminding canteen break-ins, pretending to smoke just to watch teachers go "mental," and locking a teacher in a cupboard. "That was pretty bad," Wilson admits, "because she fell over once, in the cupboard. But she was a really mean teacher." If she'd been instantly popular, she reasons, she wouldn't have the personality she has now. And the personality is working for her.

Wilson's parents were professional dog showers and beagle breeders; when she was young, they traveled around the continent selling pet products from a yellow caravan. "We were basically carnies," she says. She was named after a singer who performed at her parents' wedding, and as her mother was partial to "theming" her puppy litters, Wilson's younger siblings—Liberty, Annachi, and Ryot—got the same treatment.

Wilson did well in school and thought she'd go into law or politics. "I wasn't an extroverted kid," she says. "I was very academic, and very introverted." After high school, she deferred her acceptance to a dual-degree program in arts and law at the University of New South Wales to spend a year as a Rotary International Youth Ambassador in southern Africa. In Mozambique, she contracted the malarial bug she credits with launching her career. Delirious, Wilson hallucinated winning an Oscar. After returning home, she joined the Australian Theatre for Young People and started college at the same time. "I just had this belief that I could do it," she says. "I watched a lot of Oprah, and Oprah's like, 'If you get a whisper of something, you should believe it.' But this was a full-blown hallucination!"

After a few years at ATYP, she found that her classmates were getting agents and parts in soap operas. "No one was interested in me," she says, laughing. "All the roles were for, like, 'Bikini Girl,' age 18. So I thought, I know, I'll write my own characters, and then people can see what I can do."

Wilson wrote the stage musical The Westie Monologues, in which different female characters talk about things like love and body image. The show, which she also produced and acted in, became a hit, got backed by an Australian TV network, and ran for three seasons in Sydney. A year later, she won a scholarship to study acting in New York, and trained at Second City, the improv-based sketch-comedy theater. Still, Wilson was reluctant to let her investment in school go to waste. ("It was very James Franco of me.") In 2009, she graduated with a BA in arts and a BA in law, and then took off for Los Angeles. (She has never practiced law but still negotiates her own contracts, retaining ownership of characters she's created whenever she can.)

Within days of arriving, Wilson signed with William Morris Endeavor, which quickly led to an audition for Judd Apatow and director Paul Feig for what became Melissa McCarthy's part in Bridesmaids. Wilson went all out during the improvisation, pushing Wiig's buttons and trying to get a rise out of her.

"She was so different from anyone I'd ever seen," Feig says of Wilson's fearlessness in both line delivery and physicality. It's a gestalt Feig describes as a kind of "intellectual flightiness." What looks like imprecision is actually incredibly nuanced and thoughtfully constructed. Wiig describes her this way: "I think sometimes you have to become familiar with someone or get used to them before you truly see how funny they are, but with Rebel it was instant. She was instantly brilliant."

Feig was so impressed that after meeting Wilson's now roommate Lucas and noticing their resemblance, he rewrote the roommates for them. With their pillowy bodies, lunar pallor, and outrageous oddball sensibility, Wilson and Lucas stole scene after scene as the most creepily inappropriate siblings ever. If Lucas' Gil, who looked like an overgrown baby, was weird, his sister Brynn was outright bizarre, pouring a bag of frozen peas down her back to reduce the swelling of a free tattoo of a Mexican tequila worm she got from a guy in a van. In a clip that only made it into the film's unrated version, Wilson and Lucas sit in a bathtub together while he shaves her underarms. "It upset audiences so much," Feig recalls, laughing. "It was hilarious. People would get all upset about it in the test screenings."

Feig remembers that after Wilson had wrapped her small part, she came by the set to say hello. "She was there auditioning for some little part on a second-rate sitcom, and I remember thinking, Wow, really? Those days are numbered, because people are going to be coming after her big-time. To me, it was like already this person's a star."

Next, Wilson played the straight girl—but with no less impact—in Bachelorette. Cast as the bride, Wilson turned the typical raunchy rom-com tropes inside out—she was the confident, successful friend who was marrying the hot guy and, incidentally, happened to be plus-size—while wispy bridesmaids Kirsten Dunst, Lizzy Caplan, and Isla Fisher wrestled viciously with their own insecurities. But it was Pitch Perfect, last year's Glee-like comedy about an all-girls a cappella group that goes from uptight mediocrity to freaky, exuberant glory, that sealed her popularity. Wilson plays a bawdy, "mermaid dancing," "horizontal running," irrepressibly charming Tasmanian singer who calls herself "Fat Amy" so that "twig bitches" like their queen-bee captains don't do it behind her back—and who can really sing. Anna Kendrick may have played the ostensible lead, but it's almost impossible not to think of it as Wilson's movie.

"Fat Amy was the sexiest character in Pitch Perfect," says Lucas, giving voice to a widely held opinion. "And the funniest character, and the smartest character. And that comes from Rebel…from her improvising and playing. She's got bigger balls than any man I know."

In the writers' room of Super Fun Night, Wilson, dressed in black pants and a royal blue shirt, her hair in her trademark high ponytail, seems totally in her element.

On the show, which was initially developed as a three-camera sitcom for CBS before being re-shot as a single-camera (à la 30 Rock and The Office), Wilson plays Kimmie, a successful lawyer who spends Friday nights at home with her dorky friends Helen-Alice (Liza Lapira) and Marika (Lauren Ash) until it dawns on them to venture out into the world. In Wilson's words, "They go, 'Why do we have to be like that? Just because we're not superrich, or superhot, or whatever. We can still go out and have fun!' "

The story line is close to her heart. While Wilson and her sister Liberty were in college, Liberty worked at a candy factory and would bring home the "off-cuts," and the sisters would spend evenings watching movies and eating reject candy. "We thought it was awesome," Wilson says. "And then I kind of thought, Well, maybe this isn't so awesome, maybe I should be getting out there more and experiencing new things."

Wilson is up-front about her desire to make her show not just funny but meaningful, particularly to a strata of womanhood that isn't much represented elsewhere. Kimmie looks nothing like the girls that dominate network sitcoms, yet she's confident in her right to have a good life. Wilson "plays winners," Lucas observes. "And I think that's quite an original take."

Part of her own winning comedic combination is Wilson's physical humor, of which the show has plenty. Its genius resides in her ability not to make you feel uncomfortable with her body, but, rather, to make you feel uncomfortable about your uncomfortableness with her body. So it's totally believable when she says, "Sometimes I feel sorry for the actresses who have to be superglamorous in the movies. And then you're sitting there at lunch and never really eat anything. I'd much rather be doing what I'm doing." Then she adds, "In comedy, you have to use your physicality as well, and sometimes you get criticism [for that]. But if I had a big nose, I'd always use that, because that's what you have to do."

Earlier this year, Wilson said on an Australian talk show that she'd ended a contract with Jenny Craig after losing 30 pounds because her filming commitments in America required her to "sign contracts where you can't change your physical appearance." Somewhere in this clause lurks the assumption that Wilson wouldn't be as funny if she were thinner. That it's her body type—and not her brilliant, brazen, crazy mind—that's funny. Which is, in a word, nuts.

Flanked by nine other writers, plus four assistants, Wilson sits at the head of a huge table. Next to her are show runner and executive producer John Riggi, formerly of 30 Rock, and co–executive producer Brent Forrester, who came from The Office. Forrester is leading a discussion about future episodes, but ultimately it's Wilson who has final say. The staff is pitching ideas for possible Friday-night adventures for Kimmie, Marika, and Helen-Alice, and Wilson is on a roll. She doesn't pitch ideas so much as she lobs them from the baseline in her trademark slow, deliberate deadpan.

Among the suggestions: dog track, dog fight, silent disco, poetry slam, pheromone party, and cult. The cult episode is a running joke in the room, just like the fact that her tangential anecdotes tend to culminate in someone winding up dead. Most of the scenarios sound unlikely to see the light of day on network TV. But then, network TV has never seen a Rebel Wilson before.